scholarly journals Effect of Surface Type on the Flow Characteristics in Shale Nanopores

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Shiyuan Zhan ◽  
Yuliang Su ◽  
Mingjing Lu ◽  
Mingyu Cai ◽  
Jingang Fu ◽  
...  
Keyword(s):  
Pore Size ◽  
Shale Gas ◽  
Adsorption Layer ◽  
Flow Behavior ◽  
Knudsen Layer ◽  
Flow Mode ◽  
Migration Behavior ◽  
Gas Migration ◽  
Surface Type ◽  
Gas Flux

The underlying mechanism of shale gas migration behavior is of great importance to understanding the flow behavior and the prediction of shale gas flux. The slippage of the methane molecules on the surface is generally emphasized in nanopores in most predicted methods currently. In this work, we use molecular dynamic (MD) simulations to study the methane flow behavior in organic (graphene) and inorganic (quartz) nanopores with various pore size. It is observed that the slippage is obvious only on the graphene nanopores and disappeared on the quartz surface. Compared with the traditional Navier-Stokes equation combined with the no-slip boundary, the enhancement of the gas flux is nonnegligible in the graphene nanopores and could be neglected in the quartz nanopores. In addition, the flux contribution ratios of the adsorption layer, Knudsen layer, and the bulk gas are analyzed. In quartz nanopores, the contributions of the adsorption layer and the Knudsen layer are slight when the pore size is larger than 10 nm. It is also noted that even if the Knudsen number is the same, the flow mode may be various with the effect of the pore surface type. Our work should give molecular insights into gas migration mechanisms in organic and inorganic nanopores and provide important reference to the prediction of the gas flow in various types of shale nanopores.

scholarly journals Review of Formation and Gas Characteristics in Shale Gas Reservoirs

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5427
Author(s):  
Boning Zhang ◽  
Baochao Shan ◽  
Yulong Zhao ◽  
Liehui Zhang
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Shale Gas ◽  
Physical Parameters ◽  
Gas Reservoirs ◽  
Shale Formations ◽  
Adsorbed Gas ◽  
Shale Gas Reservoirs ◽  
Longmaxi Shale

An accurate understanding of formation and gas properties is crucial to the efficient development of shale gas resources. As one kind of unconventional energy, shale gas shows significant differences from conventional energy ones in terms of gas accumulation processes, pore structure characteristics, gas storage forms, physical parameters, and reservoir production modes. Traditional experimental techniques could not satisfy the need to capture the microscopic characteristics of pores and throats in shale plays. In this review, the uniqueness of shale gas reservoirs is elaborated from the perspective of: (1) geological and pore structural characteristics, (2) adsorption/desorption laws, and (3) differences in properties between the adsorbed gas and free gas. As to the first aspect, the mineral composition and organic geochemical characteristics of shale samples from the Longmaxi Formation, Sichuan Basin, China were measured and analyzed based on the experimental results. Principles of different methods to test pore size distribution in shale formations are introduced, after which the results of pore size distribution of samples from the Longmaxi shale are given. Based on the geological understanding of shale formations, three different types of shale gas and respective modeling methods are reviewed. Afterwards, the conventional adsorption models, Gibbs excess adsorption behaviors, and supercritical adsorption characteristics, as well as their applicability to engineering problems, are introduced. Finally, six methods of calculating virtual saturated vapor pressure, seven methods of giving adsorbed gas density, and 12 methods of calculating gas viscosity in different pressure and temperature conditions are collected and compared, with the recommended methods given after a comparison.

Molecular dynamics of methane flow behavior through realistic organic nanopores under geologic shale condition: Pore size and kerogen types

2020 ◽  
Vol 398 ◽  
pp. 124341 ◽  
Author(s):  
Zheng Sun ◽  
Xiangfang Li ◽  
Wenyuan Liu ◽  
Tao Zhang ◽  
Minxia He ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Pore Size ◽  
Flow Behavior ◽  
Methane Flow

scholarly journals Water-Gas Two-Phase Flow Behavior of Multi-Fractured Horizontal Wells in Shale Gas Reservoirs

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 664 ◽  
Author(s):  
Lei Li ◽  
Guanglong Sheng ◽  
Yuliang Su
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Flow Behavior ◽  
Horizontal Wells ◽  
Gas Production ◽  
Phase Flow ◽  
Gas Reservoirs ◽  
Two Phase ◽  
Fractured Horizontal Wells ◽  
Water Gas

Hydraulic fracturing is a necessary method to develop shale gas reservoirs effectively and economically. However, the flow behavior in multi-porosity fractured reservoirs is difficult to characterize by conventional methods. In this paper, combined with apparent porosity/permeability model of organic matter, inorganic matter and induced fractures, considering the water film in unstimulated reservoir volume (USRV) region water and bulk water in effectively stimulated reservoir volume (ESRV) region, a multi-media water-gas two-phase flow model was established. The finite difference is used to solve the model and the water-gas two-phase flow behavior of multi-fractured horizontal wells is obtained. Mass transfer between different-scale media, the effects of pore pressure on reservoirs and fluid properties at different production stages were considered in this model. The influence of the dynamic reservoir physical parameters on flow behavior and gas production in multi-fractured horizontal wells is studied. The results show that the properties of the total organic content (TOC) and the inherent porosity of the organic matter affect gas production after 40 days. With the gradual increase of production time, the gas production rate decreases rapidly compared with the water production rate, and the gas saturation in the inorganic matter of the ESRV region gradually decreases. The ignorance of stress sensitivity would cause the gas production increase, and the ignorance of organic matter shrinkage decrease the gas production gradually. The water film mainly affects gas production after 100 days, while the bulk water has a greater impact on gas production throughout the whole period. The research provides a new method to accurately describe the two-phase fluid flow behavior in different scale media of fractured shale gas reservoirs.

The Effect of Pore Size on Shale Gas Recovery with CO2 Sequestration: Insight into Molecular Mechanisms

2019 ◽  
Vol 33 (4) ◽  
pp. 2897-2907 ◽  
Author(s):  
Jian Liu ◽  
Hui Xie ◽  
Qin Wang ◽  
Shiyong Chen ◽  
Zhiming Hu
Keyword(s):  
Pore Size ◽  
Shale Gas ◽  
Co2 Sequestration ◽  
Molecular Mechanisms ◽  
Gas Recovery ◽  
Insight Into

A Study on Gas Migration Behavior in Buffer Material using X-ray CT Method

2006 ◽  
Vol 932 ◽  
Author(s):  
K. Tanai ◽  
M. Yui
Keyword(s):  
Water Saturation ◽  
Gas Injection ◽  
Swelling Pressure ◽  
Digital Data ◽  
Migration Behavior ◽  
Gas Migration ◽  
Migration Test ◽  
X Ray ◽  
Compacted Bentonite ◽  
Buffer Material

ABSTRACTThis paper presents a study on gas migration behavior in a bentonite specimen with the aid of X-ray computer tomography (CT) scan data. The laboratory experiment was carried out to clarify gas migration behavior through saturated, compacted bentonite. X-ray CT was used to estimate the spatial distribution of gas and water saturation during gas migration test in the bentonite. For the gas migration test, the controlled flow rate of gas injection was adopted for pre-compacted samples of Kunigel V1 bentonite using helium gas, which is safer than hydrogen gas.A specimen was isotropically consolidated and saturated by synthetic seawater, simultaneously, by applying a backpressure. This was followed by injecting the gas using a syringe pump. Inlet and outlet gas fluxes were monitored. This test exhibited a significant threshold pressure for breakthrough, somewhat larger than the sum of the swelling pressure and the backpressure.The procedure of the X-ray CT measurement is as follows; i) measurement of the initial condition (saturated condition) of the compacted bentonite, ii) measurement of the gas injection condition as a function of time. The digital data obtained from the X-ray CT usually includes some noise. The stacking method can reduce the noise in CT values and enables to identify the gas migration area. The results indicate that gas is transported through preferential pathways in compacted bentonite, and is not homogenous.

Characteristics of Lower Paleozoic Black Shale Reservoir in Weixin District of Northern Yunnan Province

2012 ◽  
Vol 616-618 ◽  
pp. 217-222 ◽  
Author(s):  
Wei Guo ◽  
Hong Lin Liu ◽  
Xiao Bo Li ◽  
Hua Qing Xue
Keyword(s):  
Pore Size ◽  
Black Shale ◽  
Shale Gas ◽  
Yunnan Province ◽  
Total Content ◽  
Gas Content ◽  
Carbonaceous Shale ◽  
Rock Series ◽  
Lower Paleozoic ◽  
Black Rock Series

The North area of Yunnan Province is one of favorable target areas for prospecting shale gas of marine hydrocarbon reservoirs in South China, with the black rock series developed well at Lower Cambrian Niutitang Formation and Lower Silurain Longmaxi Formation. The black rock series can be classified into seven types of lithofacies，including black shale，siliceous shale， calcarleous shale，silty shale，carbonaceous shale，argillaceous siltstoue and carbonatite. The total content of organic carbon is 0.02% to 9.37%.The organic matter is overmature，with 2.05%～3.62% of Ro and dominated by type II-kerogen. The microporosity is dominated by the micropores，with pore size less than 10nm, secondly is foraminules with pore size ranging from 10nm to 100nm. The shale gas content is low overall，only 0.42 stere per ton average，and variety range is relatively large. Our research shows the content of plagioclase, carbonate and clay inflect the content of shale gas in the area of relieved synclines and less fault.

Dynamic Dispersion Coefficient of Solutes Flowing in a Circular Tube and a Tube-Bundle Model

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Xiaoyan Meng ◽  
Daoyong Yang
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Circular Tube ◽  
Dispersion Coefficient ◽  
Tube Bundle ◽  
Flow Behavior ◽  
Dimensionless Time ◽  
Full Time ◽  
Dispersion Coefficients

Mathematical formulations have been proposed and verified to determine dynamic dispersion coefficients for solutes flowing in a circular tube with fully developed laminar flow under different source conditions. Both the moment analysis method and the Green's function are used to derive mathematical formulations, while the three-dimensional (3D) random walk particle tracking (RWPT) algorithm in a Cartesian coordinate system has been modified to describe solute flow behavior. The newly proposed formulations have been verified to determine dynamic dispersion coefficients of solutes by achieving excellent agreements with both the RWPT results and analytical solutions. The differences among transverse average concentration using the Taylor model with and without dynamic dispersion coefficient and center-of-mass velocity are significant at early times but indistinguishable when dimensionless time (tD) approaches 0.5. Furthermore, compared to solutes flowing in a 3D circular tube, dispersion coefficients of solutes flowing in a two-dimensional (2D) parallel-plate fracture are always larger for a uniform planar source; however, this is not always true for a point source. Solute dispersion in porous media represented by the tube-bundle model is greatly affected by pore-size distribution and increases as standard deviation of pore-size distribution (σ) increases across the full-time scale.

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